The invention relates to a winding machine for web material, such as paper or cardboard webs, of the kind comprising at least one roll, against which a winding reel is supported, a guide carriage connected to each respective end of a core of the winding reel, a thrust motor acting on the guide carriage, the force of said motor controlling the line pressure between the reel and the roll and being detected by a dynamometer, and a friction brake for damping vibrations of the winding reel.
The web material is wound onto such winding machines at high velocity. Non-circularity of and imbalances in the winding reel result in strong vibrations in the guide carriages acting on both sides of the winding reel. Consequently friction brakes were installed in the guide carriages to dampen the vibrations. These brakes act on guides of winding frames, on which the carriages are guided during the winding operation. Thrust motors act upon the guide carriages, and, with an increase in the diameter of the winding reel, they relieve the roll, against which the winding reel is supported, from a part of the winding weight. The extent by which this weight is relieved is controlled during the winding operation so that the winding hardness to be produced in the winding reel is influenced above the level of the line pressure effective between the winding reel and the roll. Therefore a dynamometer is provided to detect the force of the thrust motors acting on the winding reel. However in the known winding machines not only the force of the thrust motors acting on the guide carriages, but also the braking forces caused by the brakes are measured when the friction brakes become effective. Therefore it is not possible to control the line pressure accurately because of changes in friction on the guides of the carriages.